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MG MGF Technical - Brake caliper mount centre

Does anyone know the mount centre (distance between the centre of the two bolts) of a stock MGF rear caliper?
Will Munns

300mm centre spacing with 10mm holes whose centres are placed some 29mm from the caliper centreline - hope that makes sense Will? I *think* that the front is the same as the rear on the F.

Is this for what I think it is Will?
Rob Bell

Of course ;-)

Unfortunatly the Metro K-hubs are the wrong PCD (did my neck in getting the buggers off) apparently the Metro A-hubs are the _right_ PCD, so I'm back on saturday! (as long as the driveshafs match....)
The mount cenmtres are 8cm apart, which doesn't seem to match anything :-(
Will Munns

Rob, surely the caliper holding bolts are not 300mm apart.

d mottram

Errrrr.... :o(

David, I confess to having cut and pasted that bit of info from an email sent to me from Roger Parker (I'm still looking into alternative rear brake calipers and rotors). Roger, as we know, is a trusted source of information like this - but a hole centre 30 cm apart does sound like a lot - when I actually think about it!!!

Do you know what the figures are David? You must have measured things up when you were sorting out your front brakes?
Rob Bell

I will check at the weekend. I have it written down somewhere since I did use it in the conversion.
d mottram

With those measurements you will need at least 24" diameter wheels, lol, Go for it;-))
BTW the rear ctrs are different and if you get stuck Will I can measure you a set.
Mike.
mike

You're not wrong! :o/ Methinks a typo somewhere... :o(
Rob Bell

Rob, beeing the "brake affaire" a complete nightmare for me, I'll be very interested on what you do (or anything another one does), so please share your ideas...

Tx
Spinder00

The idea I have is actually very simple Jose - what I'd like to do is simply scale up what is already there.

Let me expand on that a little further: the MGF uses the same size discs front and rear (albeit, at the rear, the disc is thinner and non-ventilated - but this has no direct effect on brake force until excess heat becomes the limiting factor). The standard brake bias valve is therefore configured to provide the ideal brake balance for such a system.

The other variable is the piston size (piston area). The AP racing for pot caliper has a total piston area very close to that used by the standard front caliper. This means that for any given movement of the brake pedal, the force applied to the brake pads is effectively the same (give or take) for the AP caliper and standard Rover caliper.

So if we want to maintain the standard brake balance with larger brake disc rotors, and plan to use calipers that allow the use of larger pads (good for heat dissipation, pad longevity), we need to maintain the same brake leverage front and rear by using the same size rotors and same piston areas in proportion to what's there as standard. The brake bias will then look after itself.

Given that the AP racing caliper is a full production item, meaning spare parts are readily available, it makes sense to use these discs and rotors at the front.

What I'd like to do is use the AP 304mm discs at the rear - but for that, we're going to need to source a suitable rear caliper - one that retains a mechanical handbrake linkage. The Lotus Elise rear caliper could be suitable, but I need to find out the piston area. If this is suitable, then it is a case of sourcing a couple of calipers, and having an adapter made up...
Rob Bell

Tx Rob. Beeing less ambitious, I was thinkin something in the same way, using the original callipers, but two sets of big disc adaptors (285 mm front and rear) to maintain unchanged the brake balance. I think that the greater leverage, and better pads (mintex 1144 seems to be the choice) will be enough to improve the poor braking performances.

But here in Spain, when you want to change the size of the brake rotors, you have to obtain a letter from the builder saying that this size exist in this model of car or you'll fail the MOT.

No problem with front one, as the 305 mm disc exist, but the rear one is limited then to 240.

Still investigating if a need a technical project from an ingeneer and how much does it cost, or maybe I could have the letter of MGR only saying 305 mm are used in the car, and making the MOT service believe that is 305 all round...

Ufffffff!!!!!

P.S.: Have you talked with Michael Marcoulacos, the greek fellow who owns this heavily modified 160 trohpy to obtain the pics of his modified AP rear callipers? Maybe he has the solution...
Spinder00

This thread was discussed between 15/02/2005 and 26/02/2005

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